Once you have structured data code with you, basically add it to HTML code from the webpage. For CMSes it depends upon the file where the HTML of your topic is coming from. It could either be header.php or any other file during the theme folder. Below I’m outlining this https://addons.prestashop.com/it/seo-indicizzazione-naturale/31857-google-rich-snippet-automatico-json-ld-open-graph-seo.html